A nonparallel, nonisometric synthetic graft augmentation of a patellar tendon anterior cruciate ligament reconstruction. A model for assessment of stress shielding.
The potential for a rigidly fixed synthetic graft placed in the over-the-top position to be stress shielding/stress sharing with the patellar tendon autograft was assessed in a primate model. A patellar tendon autograft was placed anatomically and tensioned at 2 pounds for all of the groups. In the augmented animals, a 30 strand braided graft 10 cm in length of expanded polytetrafluoroethylene was tightened with the knee in full extension. After 6 months of unrestricted cage activity the animals were sacrificed and biomechanical testing performed. The augmented patellar tendon autografts demonstrated less laxity in extension as compared to the autografts alone. A minimal decrease in the load and stiffness to failure for the augmented groups as compared to the nonaugmented knees was noted. However, both the reconstruction groups had a significant decrease in the load to failure at 6 months (50% of the normal ACL). In summary, this study demonstrated that a synthetic graft augmentation can be performed in the over-the-top position and minimize knee laxity, especially during terminal extension. With this technique, the laxity was minimized while the incorporation and strengthening of the biologic autograft occurred at a rate similar to the unaugmented reconstruction.
McCarthy
J A
JA
Washington University Hospital, St. Louis, Missouri.
Steadman
J R
JR
Dunlap
J
J
Shively
R
R
Stonebrook
S
S
D000818:Animals; D005069:Evaluation Studies as Topic; D005260:Female; D007719:Knee Joint / Q000601:surgery*; D008023:Ligaments, Articular / Q000601:surgery*; D008251:Macaca; D008297:Male; D019736:Prostheses and Implants; D013314:Stress, Mechanical; D013710:Tendons / Q000637:transplantation*; D014182:Transplantation, Autologous; D014183:Transplantation, Heterologous